Tire defect tester

ABSTRACT

A tire defect tester and a method of operation are disclosed. In one aspect, the tire defect tester includes a first electrode arranged to direct energy toward a tire, and a second electrode arranged on an opposite side of the tire from the first electrode to receive energy passing through the tire from the first electrode. The tire defect tester further includes an energy sensor electrically connected to the second electrode and a fault indicator circuit responsive to the energy sensor and configured to indicate the presence of a flaw upon energy above a threshold level being sensed at the second electrode.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S.application Ser. No. 12/129,462, entitled “TIRE DEFECT TESTER,” filedMay 29, 2008, which claims priority to U.S. Provisional PatentApplication No. 60/932,310, filed May 29, 2007, the entire disclosuresof which applications are expressly incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates generally to inspection of tire defects.In particular, the present disclosure relates to a tire defectinspection system.

BACKGROUND OF THE INVENTION

New tires are expensive. As a result, replacing and maintaining tirescan be an economic burden for companies and individuals who manage alarge fleet of vehicles or otherwise place excessive wear on theirtires. Replacing tires can also be a burden for those of modest means.As a result, it is becoming increasingly important to repair damagedtires rather than replace them with new tires. Repairing a damaged tireis usually very simple and inexpensive, especially repairing simpleholes or objects that become embedded in the treaded portion of thetire.

Diagnosis is the first step in repairing a damaged or flawed tire. It isnecessary to ascertain if any foreign objects are embedded in the treadportion of the tire or if any cracks, fissures, or holes exist therein.If such defects are found to exist, the tire can be repaired. If thedefect is not found, the tire must be replaced.

There are several existing techniques for inspecting a tire. One suchtechnique is visual inspection. Visual inspection consists of rotating atire on a mounting stand, while an inspector visually observes the treadportion of the tire as it passes beneath his gaze. Visual inspection ofa tire tends to be slow and time consuming. More importantly, however,this method for searching for defects is, at best, unreliable. This isbecause some defects are so minute that they escape the detection ofeven a trained, experienced observer. Even these undetected defects canweaken the tire and become a hazard to vehicles operating at high ratesof speed.

In an attempt to solve some of the problems inherent in visualinspection, other types of testing techniques have been devised. Onesuch method involves over inflating a tire and either immersing the tirein a fluid or applying a fluid to the outer surface thereof. A leak ofair through an orifice or fissure can be detected visually more readilyby the observation of a bubbling effect, which will occur at thelocation of the defect. This method, however, will not detect defectsother than well defined holes that pass all the way through the treadedportion of a tire.

More complex systems for detecting tire defects also exist. In one suchsystem, the tread portion of a tire is sandwiched between a pair ofelectrodes across which a high voltage electrical potential isgenerated. With this system, if objects such as nails are embedded inthe tread portion of the tire or if defects such as orifices or fissuresexist, the voltage applied across the electrodes will cause arcing atthe point of foreign object or defect. To inspect the complete tire, aninspection device typically rotates the tire such that the tread portionpasses between the electrodes. An electronics package generally isincluded in conjunction with the electrodes, and can stop rotation ofthe tire and actuate an alarm once a defect is detected by arcing acrossthe electrodes. Pinpointing the location of the defect is, thereby,facilitated.

However, even with existing systems, only a general location of the flawin the tire determined. Additional information about the type of defector number of defects in the tire or a series of tires could be helpfulin repairing tires, as well as identifying a source of the flaw.

Furthermore, each of these tire inspection systems have limitedcapabilities and only detect the presence or absence of certain types ofdefects. These inspection systems cannot detect any characteristics orthe nature of the flaw itself. Nor can the systems record relatedstatistical information.

SUMMARY

In accordance with the following disclosure, the above and otherproblems are addressed by the following:

In a first aspect, a tire defect tester is disclosed. The tire defecttester includes a first electrode arranged to direct energy toward atire, and a second electrode arranged on an opposite side of the tirefrom the first electrode to receive energy passing through the tire fromthe first electrode. The tire defect tester further includes an energysensor electrically connected to the second electrode and a faultindicator circuit responsive to the energy sensor and configured toindicate the presence of a flaw upon energy above a threshold levelbeing sensed at the second electrode.

In a second aspect, a method of testing tires for defects is disclosed.The method includes directing an energy signal toward a first locationon a surface of a tire. The method further includes detecting anattenuated energy signal on a surface of the tire opposite the firstsurface. The method also includes comparing the attenuated energy signalto a predetermined energy signal value to determine the presence of aflaw in a tire at the first location.

In a third aspect, a tire tester is disclosed. The tire tester includesmeans for directing an energy signal toward a first location on asurface of a tire, and means for detecting an attenuated energy signalon a surface of the tire opposite the first surface. The tire testeralso includes means for comparing the attenuated energy signal to apredetermined energy signal value to determine the presence of a flaw ina tire at the first location.

In a fourth aspect, a control circuit for a tire defect tester havingfirst and second electrodes on opposite sides of a tire is disclosed.The control circuit includes a pulse generator arranged to trigger avoltage pulse at a circuit output, the circuit output electricallyconnectable to a first electrode. The control circuit further includesan energy sensor arranged to receive energy from a circuit input, thecircuit input electrically connectable to a second electrode. Thecontrol circuit also includes a fault indicator circuit responsive tothe energy sensor and configured to indicate the presence of a flaw uponenergy above a threshold level being sensed at the circuit input.

In a fifth aspect, a method of detecting defects in tires using a tiretester having a control circuit is disclosed. The method includesgenerating an energy signal in a control circuit. The method includesdetecting an attenuated energy signal, and comparing the attenuatedenergy signal to a predetermined energy signal value to determine thepresence of a flaw in a tire.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top perspective view of a tire defect tester useable toimplement aspects of the present disclosure;

FIG. 2 is a fragmentary view illustrating a drive roller and crankassembly shown in FIG. 1;

FIG. 3 is a fragmentary view illustrating a roller assembly shown inFIG. 1;

FIG. 4 is a fragmentary view illustrating a first electrode assemblyshown in FIG. 1;

FIG. 5 is a schematic block diagram of a controller system useable in atire defect tester, according to a possible embodiment of the presentdisclosure;

FIG. 6 is a schematic view of aspects of a controller system useable ina tire defect tester, according to a possible embodiment of the presentdisclosure;

FIG. 7 is a further schematic view of aspects of a controller systemuseable in a tire defect tester, according to a possible embodiment ofthe present disclosure;

FIG. 8 is a schematic view of electrical systems useable in a tiredefect tester, according to a possible embodiment of the presentdisclosure;

FIG. 9 is a schematic view of a high voltage assembly useable in a tiredefect tester, according to a further possible embodiment of the presentdisclosure;

FIG. 10 is a further schematic view of a high voltage assembly useablein a tire defect tester, for use in accordance with the embodiment ofFIG. 9;

FIG. 11 is a further schematic view of a high voltage assembly useablein a tire defect tester, for use in accordance with the embodiment ofFIG. 9;

FIG. 12 is a schematic view of a power input circuit useable inconjunction with a high voltage assembly, as described in FIGS. 9-11;and

FIG. 13 is a schematic view of a control input circuit useable inconjunction with the high voltage assembly, as described in FIGS. 9-11.

DETAILED DESCRIPTION

Various embodiments will be described in detail with reference to thedrawings. Reference to various embodiments does not limit the scope ofthe claims attached hereto. Additionally, any examples set forth in thisspecification are not intended to be limiting and merely set forth someof the many possible embodiments for the appended claims.

In general, the present disclosure relates to a tire defect tester, andcontroller systems incorporated into such a tire defect tester. Throughuse of the tire defect tester of the present disclosure, tire defectsand other characteristics can be detected either automatically ormanually, with improved precision. The various systems described hereincan improve reliability and repeatability of tire defect detection.

Referring now to FIGS. 1-4, an example tire defect tester 10 isillustrated, in which aspects of the present disclosure can beimplemented. As shown in FIG. 1, the tire defect tester 10 has a tirelift 100. One possible embodiment of the tire lift 100 has a main frame102 and a subframe 104. The main frame 102 has two parallel base members106 and 108 that are connected by an intermediate member 110. Theintermediate member 110 is perpendicular to the base members 106 and108. A vertical support beam 112 projects upwardly from the intermediatemember 110. The vertical support beam 112 has a height sufficient thatthe subframe 104, and hence the tire being tested, can be raised to eyelevel for easy inspection. A flange 114 projects rearward from theintermediate member 110.

Two control panel supports 116 and (not shown) project upward from eachof the base members 106 and 108, respectively, and a control panel 118is mounted to the control panel supports. The control panel 118 houses apower supply and electronics for charging electrodes, which aredescribed in more detail below in conjunction with FIGS. 5-9.

The subframe 104 slidably engages the main frame 102. The subframe 104includes a U-shaped chassis 120 having first and second support beams122 and 124 that are parallel to one another. An intermediate portion126 is perpendicular to and extends between the first and second supportbeams 122 and 124.

A first collar 128 has three sides 130, 132 and 134. First and secondsides 130 and 132 are positioned on opposite sides of the verticalsupport beam 112 and are attached to the intermediate member 126 of thesubframe 104. The first side 130 is taller than the second side 132. Thethird side 134 extends between the first and second sides 132 and 134.The third side 134 is on an opposite side of the vertical support beam112 from the intermediate member 126 of the U-shaped chassis 120. Inthis configuration, the first collar 128 holds the U-shaped chassis 120to the vertical support frame 112. In order to add structural rigidity,angular reinforcement beams 136 and 138 extend between the first andsecond sides 130 and 132 of the collar 128 and the intermediate portion126 of the U-shaped chassis 120.

A vertical subframe beam 140 extends upward from the third side 134 ofthe first collar 128 and is positioned proximal to a rear surface of thevertical support beam 112 of the main frame 102. A second collar 142 ismounted around the vertical support beam 112 of the main frame 102 andis attached to the vertical subframe beam 140.

A first cylinder flange 144 extends rearward form the third side 134 ofthe first collar 128. A second cylinder flange 146 extends rearward fromthe vertical subframe beam 140 and is proximal to the second collar 142.A hydraulic cylinder 148 is vertically oriented and extends between thefirst and second cylinder flanges 144 and 146. The hydraulic cylinder148 has a cylinder arm 150 that projects downward and passes through thefirst cylinder flange 144. The cylinder arm 150 is attached to theflange 114 of the main frame 102.

A horizontally oriented bar 152 is attached to the second collar 142,and has a bracket 154 extending downward from one end. A verticalstabilization roller 156 is mounted to the bracket 154 and facesrearward toward the vertical support beam 112 of the main frame 102. Thebar 152 slidably engages the second collar 142 so that the position ofthe vertical stabilization roller 156 is adjustable.

A hydraulic valve 158 is mounted on the front of the bracket 154 and isconnect to the hydraulic cylinder 148 via hoses (not shown). An operatorcan actuate the valve 158 to cause the cylinder arm 150 to eitherretract into or extend from the hydraulic cylinder 148. Causing thecylinder arm 150 to extend from the hydraulic cylinder 148 will causethe first and second collars 128 and 142 to slide along the verticalsupport beam 112 of the main frame 102, and thus the subframe 104 tomove upward. Likewise, causing the cylinder arm 150 to retract willcause the subframe 104 to move downward relative to the main frame 102.In order to aid movement of the subframe 104, bushings or bearings canbe placed between the first and second collars 128 and 142 and thevertical support beam 112.

An electrode bracket 160 is pivotally connected to the first side 130 ofthe first collar 128, and is positioned toward the top edge of the firstside 130. An insulating bracket 162 is detachably connected to theprojecting end of the electrode bracket 160, and a first electrode 164is mounted to the insulating bracket 162. The first electrode 164 iselectrically connected to the control panel 118 with wires (not shown).The first electrode 164 is described in more detail below. An advantageof pivotally mounting the electrode bracket 160 is that the position ofthe first electrode 164 can be adjusted slightly to ensure good contactwith the inner surface of a tire's tread portion. Additionally, aninterlock (not shown) can be operatively connected between the firstelectrode 164 and the electrode bracket 160. The interlock would preventthe first electrode 164 from being energized when not properly attachedto the electrode bracket 160.

First and second drive rollers 166 and 168 are mounted to the first andsecond support beams 122 and 124, respectively, of the U-shaped chassis120 with bearing assemblies 169 and (not shown). The first roller 166 ismade from an insulating material such as rubber. Rubber is advantageousbecause it provides traction with a tire. The second roller 168 has ribsextending along its length to provide traction with a tire that ismounted in the tire lift. Additionally, the second roller 168 is formedfrom a metallic roller to form a second electrode 170. The second roller168 is then electrically connected to the circuitry in the control panel118 and is grounded. This distance is advantageous because the treadportion of a tire can rest on the first and second rollers 166 and 168.

Referring to FIGS. 1 and 2, a bracket 172 is mounted on the end of thesecond support beam 124 of the U-shaped chassis 120. A spindle 174 ismounted to the bracket 172 by a bearing assembly 176. A first sprocket178 and a first hand wheel 180 are mounted on the spindle 174. In turn,the second drive roller 168 has an axle 182 that extends outward fromone end. A second sprocket 184 is mounted on the axle 182 of the seconddrive roller 168. A chain 186 extends around the first and secondsprockets 178 and 184. Additionally, a cowling 188 (not shown in FIG. 2)provides protective covering for the chain 186, the first sprocket 178,and the second sprocket 184.

In an alternative embodiment, a motor (not shown) is mounted to thesubframe 104 in place of the first hand wheel 180. The motor wouldpermit automatic rotation of the second drive roller 168, and henceautomatic rotation of the tire.

Referring to FIGS. 1 and 3, a bracket 190 is mounted on the end of thefirst support beam 122 of the U-shaped chassis 120 and an electricalswitch 192 is mounted on the bracket 190. The electrical switch isconnected to the power supply and circuitry in the control panel viawires (not shown). Actuating the electrical switch 192 will energize thefirst and second electrodes 164 and 170.

A screw mechanism 194 is also rotatably mounted to the first supportbeam 122 of the U-shaped chassis 120 by first and second bearingassemblies 196 and 198. The screw mechanism 194 has a treaded rod 200that has first and second portions 202 and 204. The first portion 202has threads in one direction, and the second portion 204 has threads inan opposite direction. A second hand wheel 206 is mounted on the end ofthe threaded rod 200.

A first roller bracket 208 is mounted to the first portion 202 of thetreaded rod 200, and a second roller bracket 210 is mounted to thesecond portion 204 of the thread rod 200. First and second rollers 212and 214 are mounted to the first and second brackets 208 and 210,respectively, and are then horizontally spaced. The first and secondrollers 212 and 214 are arranged and configured to be positionedproximal to the sidewalls of a tire. The distance between the first andsecond rollers 212 and 214 is adjustable by turning the second handwheel 206. Turning the second hand wheel 206 in one direction will causethe first and second rollers 212 and 214 to move closer together, andturning the second hand wheel 206 in an opposite direction will causethe first and second rollers 212 and 214 to move farther apart.

Referring now to FIG. 4, the first electrode 164 has two conductiveplates 216 and 218 that are isolated by insulators 220 and 222 and aremounted to the insulating bracket 162. A first pair of wire lobes 224and 226 are in electrical communication with the first conductive plate216. The first pair of wire lobes 224 and 226 project downward so thatthey engage the inner surface of the tire's 228 tread portion 230. Asecond pair of wire lobes 232 and 234 are in electrical communicationwith the second conductive plate 218 and project from opposite sides ofthe electrode 162. In this configuration, the second pair of wire lobes232 and 234 engage the region between the tire's tread portion 230 andsidewalls 236 and 238.

Additionally, a series of beaded chains 240 hang downwardly from theelectrode 164. The first pair of lobed wires 224 and 226, the secondpair of lobed wires 132 and 134, and the beaded chains 240 are allelectrified when the first electrode 164 is energized. One type ofelectrode that can be used is model no. INTER-NDT-LT (called Probe—forLight Truck), which is manufactured by the Paul E. Hawkinson Company,having its principal place of business in Minneapolis, Minn.

Other example tire defect testers may be used as well, in accordancewith the present disclosure. Example tire defect testers, and systemsfor detecting flaws in tires, are shown in U.S. Pat. No. 6,050,136,filed Apr. 16, 1998, and U.S. Pat. No. 4,516,068, filed Apr. 16, 1983.The disclosures of each of these patents are hereby incorporated byreference in their entireties.

In use, an operator will lower the subframe 104 so that the U-shapedchassis 120 is proximal to the base members 106 and 108 of the mainframe 102. The worker then removes the first electrode 164 andinsulating bracket 162 from the electrode bracket 160 to clear room fora tire. The operator rolls a tire onto the U-shaped chassis 120 so thatthe tread portion 330 of the tire 228 rests on the first and seconddrive rollers 166 and 168.

In this position, the stabilization roller 156 is proximal to the outersidewall 236 of the tire 228. The operator can adjust the position ofthe stabilization roller 156 by sliding the bar 152 relative to thesecond collar 142. Additionally, the tire 228 is positioned between thefirst and second horizontally spaced rollers 212 and 214. The operatorcan then rotate the second hand wheel 206 and adjust the distancebetween the first and second horizontally spaced rollers 212 and 214.The stabilization roller 156, as well as the first and secondhorizontally spaced rollers 212 and 214 should be proximal to thesidewalls 236 and 236 of the tire 228, but not necessarily touching thetire 228.

In this configuration, the rollers 152, 212, and 214 stabilize the tire228 while it is rotating, as described below. Stabilizing the tire 228is important because the tire 228 may wobble because of conditions suchas uneven wear in the treads or because of the narrow width of the tire228 relative to its height. Because most tires have similar sizes, theoperator typically does not need to adjust the rollers 156, 212 and 214prior to testing each tire. An adjustment needs to be made only if thereis a relatively drastic change in the size of tires being tested.

After the tire 228 is mounted, the operator will actuate the hydraulicvalve 158 and cause the cylinder arm 150 to extend, thereby raising thetire 228. The operator typically raises the tire 228 to a level wherehe/she can easily peer into the tire 228 or observe the outer surface ofthe tread portion 230 proximal to the second drive roller 168. Theoperator then positions the first electrode 164 in the tire 228 andattaches the insulating bracket 162 to the electrode bracket 160. Inthis position, the interlock will permit the electrodes 164 and 170 tobe energized. An alternative embodiment includes a mirror (not shown)operably connected to the subframe 104 and positioned so that theoperator can observe arching from the second electrode 170 withoutbending over.

Once the first electrode 164 is in place, the operator can actuate theswitch 192 and energize the first and second electrodes 164 and 170. Theoperator turn the first hand wheel 180 to rotate the tire 228, whichmoves the inner surface of the tread portion 230 against the firstelectrode 164 and the outer portion of the tread portion 230 against thesecond electrode 170. The operator watches for arcing that occurs fromeither one of the electrodes 164 or 170. The operator can also listenfor arcing, which will make a popping or cracking noise.

When an arc occurs, the operator will stop rotating the tire 228 andrelease the switch 192, which causes the electrodes 164 and 170 todeenergize. The operator can then safely mark the location of the defectfor repair. After marking the operator reenergizes the electrodes 164and 170 and continues to rotate the tire 228.

This process is continued until the entire tire 228 has been inspected.The operator then lowers the subframe 104, detaches the first electrode164, and rolls the tire 228 off the tire lift 100.

In further embodiments, particularly with respect to those embodimentsof the tire tester incorporating the circuitry described below,circuitry is provided in conjunction with the tire tester which operatesa motor and generates pulses to be applied across the electrodes.Details regarding such embodiments are described below, in conjunctionwith FIGS. 5-13.

Referring to FIGS. 5-13, various possible embodiments of electricalsystems and controllers are shown that can be used in the tire defectdetector arrangements of FIGS. 1-4, as well as with other configurationsof tire defect testers, including other embodiments of structures forelectrodes, mounting a tire, supporting a tire, and rotating a tire toan electrode arrangement.

FIG. 5 illustrates a schematic block diagram of a controller system 500useable in a tire defect tester, according to one possible embodiment ofthe present disclosure. Generally, the controller system 500 provideselectrical control and operation in a tire defect tester. The controllersystem 500 can be used in any of a variety of types of tire defecttesters; one example is the tire defect tester 10 discussed above.

In the embodiment shown, the controller system 500 includes a controlassembly 501 which includes a control microcontroller 502 interfaced toa number of input and output signals, including a start switch 504, atire type indicator 506, a flaw indicator 508, a completion indicator510, and a motor enable output 512. The control microcontroller 502 alsois configured to send and receive data via an RS-232 port 514. The tiretype indicator 506 provides an indication corresponding to the type oftire being tested (e.g. steel belted or fabric tire). The type of tiretested affects the energy applied across the tire during testing—steelbelted tires require less energy due to the conductor within the tire.The flaw indicator 508 provides an indication (e.g. sound or light)indicating the existence of a flaw in the tire. The completion indicator510 provides an indication (sound or light) indicating that the testingof that tire has completed. These indicators can correspond to LED orother displays, buzzers, or other perceptible user notifications.

In the embodiment shown, the controller system 500 includes a highvoltage assembly 515 which is interfaced to the control assembly byconnection of a complementary RS-232 port 516 to the RS-232 port 514 ofthe control assembly. The RS-232 port 516 provides a data input/outputinterface for a microcontroller 518 in the high voltage assembly, whichis in turn interfaced to a pulse charging circuit 520 and a peakdetector 522.

The pulse charging circuit 520 is connected in parallel with a capacitor524 and is used in conjunction with the microcontroller 518 to power thecapacitor 524. The pulse charging circuit 520 receives power from apower conditioning circuit 526, which, in the embodiment shown, includesa line filter 528 interconnected to a 120VAC input power supply, arectifier 530 (to which the pulse charging circuit 520 is directlyconnected), and a bias supply 532. The pulse charging circuit 520interconnects to a Silicon-Controlled Rectifier (SCR) 534, whichselectively discharges the capacitor 524 when the pulse charging circuit520 is deactivated, to provide a voltage to a transformer 536interconnected to the SCR 534 (from the discharging capacitor).

The high voltage probe 540 is powered via the transformer 536, andpulses based on the discharge from the capacitor 524. The pulses fromthe high voltage probe 540 pass through a tire under examination, to acurrent sensing module 538. The current sensing module 538 detectscurrent at an output of a high voltage probe 540. The peak detector 522,which is electrically connected to the current sensing module 538,detects peak energy received at the current sensing module 538.

In alternative embodiments of the controller system 500, othercommunicative connections can be used in place of the RS-232 ports 514,516, such as other parallel or serial data connections using synchronousor asynchronous communication protocols. Furthermore, microcontrollers502, 518 can be replaced by microprocessors or other types ofprogrammable circuits. Additional inputs to the controller system 500are possible as well.

In use, an operator initiates operation of the control system 500 bypushing the start switch 504. After a short delay, the motor starts(e.g. by activating the motor enable output 512) and the controlmicrocontroller sends a command to the high voltage assembly 515 via theRS-232 connection (interconnected RS-232 ports 514, 516) to initiate themicrocontroller 518 to trigger a high-voltage pulse. This commandincludes a setting for the peak detector A/D on the high voltageassembly 515 and a bit to indicate the steel/fabric setting (e.g. asindicated by the tire type indicator 506), which can alter the energysupplied to the high voltage probe 540.

When the high voltage assembly 515 receives the command, themicrocontroller 518 starts the pulse charging circuit 520. This circuitcharges capacitor 524 to a level determined by the setting of thesteel/fabric indicator 506. For example, the circuit can direct a lessercharge onto the capacitor in the case of a steel-belted tire than in thecase of a fabric tire, to prevent false arcing when a steel tire istested. Since the energy in a capacitor is proportional to the square ofthe voltage on the terminals of the electrodes of the system, chargingand discharging the capacitor supplies a fixed amount of energy to theelectrode (i.e. part of the high voltage probe 540). About 20milliseconds after starting the charge, the microcontroller 518 stopsthe charging circuit 520 and triggers the SCR 534, discharging thecapacitor 524 through the primary of the transformer 536. In theembodiment shown, the transformer 536 has a turn ratio of about 121:1,so a capacitor (e.g. capacitor 524) charged to about 200 volts willcreate a high-voltage pulse of about 24,200 volts on the high voltageprobe 540.

If a flaw is present on the tire, the insulation provided by the tirebetween the high voltage probe 540 and ground (e.g. shown in FIG. 6)will break down and current will flow in the secondary winding of thetransformer 536. The current sensor 538 on the high voltage assembly 515measures this energy as compared to the threshold set previously by thecommand received from the control microcontroller 502.

The result, in the form of a byte indicating the existence or absence ofa flaw, is passed back to the control microcontroller 502. If the resultwas a flaw, the control microcontroller 502 stops the motor andilluminates the flaw light (e.g. by activating the flaw indicator 508).If the result was no flaw, the control microcontroller 502 can sendanother command to the microcontroller 518 and initiates anotherhigh-voltage pulse.

In certain embodiments, the system 500 has a selectable manual mode. Inthe manual mode, a user closes a manual switch, which starts the motorand causes the high voltage microcontroller 518 to generate high-voltagepulses at a repeated rate (e.g. about a 20 ms rate). This manual mode isused to enable the operator to manually locate the actual flaw on atire.

In further embodiments, the controller system includes a set upadjustment, which corresponds to the threshold of the peak detector todetermine a flaw or no flaw condition. This adjustment occurs on thecontrol assembly 501. It is converted to a digital byte and transmittedto the high voltage assembly 515 alongside the command passed betweenthe RS-232 interfaces 514, 516.

Through use of certain embodiments of the system 500, various aspects ofevery high voltage pulse applied to the tire are controlled. In at leastsome embodiments, pulse timing, energy level, and flaw detectionthreshold are all established by software executed on the controlmicrocontroller 502 and microcontroller 518 of the high voltageassembly. For example, the control microcontroller 502 can accomplishpulse timing control by triggering each high voltage pulse of the highvoltage probe 540 separately, on a programmable, periodic basis.Similarly, the energy level of the pulse can be dictated by the controlmicrocontroller 502 and the high voltage assembly microcontroller 518,by transmitting an expected charge value and triggering a high voltageprobe pulse when an appropriate voltage is reached on the chargingcapacitor 524. Likewise, the microcontrollers 502, 518 can establish avalue for the flaw detection threshold corresponding to the total energydetected, such that a different threshold (e.g. expected energyobserved) is associated with each pulse. In such embodiments, each pulseis generated independent of all other pulses, and the results of eachpulse are independently detected and evaluated before another isgenerated. This arrangement allows the system 500 to stop on the samepulse in which a flaw is detected. This allows the system to react morequickly to detection of a flaw, thereby more accurately indicating thelocation of the flaw in the tire by halting the tire rotation at thelocation of the flaw.

In certain further embodiments (in particular embodiments employing thehigh voltage assembly of FIGS. 9-13, below), each pulse is generatedseparately. In these embodiments, each pulse can be assigned a uniqueenergy level, or differing timing or detection levels. By varying energylevels, timing, and detection levels, it may be possible to furtherprofile, measure, or grade detected flaws in tires related to type,severity, and size. For example, a tire tester can obtain a moreaccurate flaw profile across a tire by increasing the pulse frequency ofthe high voltage probe; also, the amount of energy by which the pulseexceeds a threshold energy might indicate the severity or type of aflaw. Furthermore, a large number of flaw indications in succession, ora flaw indication at even low energy levels may correspond to a largeflaw present in a tire.

Now referring to FIGS. 6, 7, and 8, schematics of circuitry useable in atire defect tester, according to certain possible embodiments of thepresent disclosure. FIG. 6 illustrates details of one of many possibleembodiments of a control block portion 600, which provides details ofcertain aspects of the control assembly 501 of FIG. 5. FIG. 7illustrates details of one of many possible embodiments of a furthercontrol block portion 700, such as can be used in conjunction with theportion 600 to form a control circuit. The control circuit, formed fromportions 600, 700, generally sends commands to a high voltage circuitfor activation/deactivation of the flaw detection tester, which in turngenerates electrical signals used to periodically activate a highvoltage probe to detect flaws in tires.

When used with the embodiment of the high voltage circuit of FIG. 8,below, a current transformer (e.g. current transformer 836 in thecircuit 800 of FIG. 8) is connected to pin X2-2 on the control block700. An approximately 10 ohm resistor (R1, shown in FIG. 8) provides thetermination for the current transformer and converts the current waveform from a high voltage probe (e.g. high voltage probe 830) to avoltage waveform. This voltage waveform is peak detected by diode U3 andC2, seen in FIG. 7. R2 provides a long decay time constant for thevoltage on C2. Because the current in the circuit portion 700 isdetermined by the energy level in the current sensor of the high voltageassembly 515, the voltage on C2 of FIG. 7 at the conclusion of the highvoltage pulse reflects that energy level. Therefore, the discharge timeof C2 R2 will also reflect the energy level and the presence of a flaw.Comparator U5 converts the saw-toothed waveform on C2 to a pulse, thewidth of which represents the amount of energy that passed through thehigh voltage probe during the last high voltage pulse. Micro controllerIC2 then measures the width of this pulse and decides whether the pulserepresents a flaw.

In operation, an operator starts the test sequence by pushing the Startbutton, connected to X1-3. This signals the microcontroller IC2 (of FIG.6) to turn off the flaw light and turn on the motor and the high voltagesignal. The high voltage circuit (seen in FIG. 7) then cycles (or ispulsed), producing a high voltage spike periodically (in the case of thecircuit of FIG. 8, every 20 ms on the high voltage probe 830). Eachpulse produces a signal to the microcontroller from the peak detector,seen as U7 of FIG. 8, and comparator U5. If one of the pulses from thecomparator circuit exceed the threshold time, which is typically about 2ms, the microcontroller turns off the motor and high voltage and turnson the flaw light, stopping the tire with the probe resting on the flaw.

In the embodiment shown, a 20 turn potentiometer Q3 is used to adjustsensitivity of the detector circuit. The potentiometer Q3 adjusts thecomparator threshold and adjusts the length of the pulse from thecomparator U5. The operator sets the potentiometer Q3 such that thesystem 700 trips only on flaws. In further embodiments, the sensitivityof the detector circuit can be set in different ways. For example, thesensitivity of the detector circuit can be set by a microcontrollerintegrated in the system, and can be programmable.

Now referring to FIG. 8, an embodiment of an electrical system 800 isshown that is useable in a tire defect tester. The electrical system 800can be used, in certain embodiments, within the system 500 above, toprovide a probe circuit driven either manually or by a control circuit.In such embodiments, the electrical system 800 generally provides thefunctionality of the high voltage assembly 515 of FIG. 5, as well as thehigh voltage probe 540 and high voltage transformer 536. In theembodiment shown, the electrical system 800 includes a pair ofcapacitors C1 802 and C2 804 that, along with a set of six resistors R1806, R2 808, R3 810, R4 812, R5 814, and R6 816, as well as a spark gap818, forms a relaxation oscillator 820. The relaxation oscillator 820portion of the electrical system 800 generates a saw-tooth wave in whichthe capacitors C1 802 and C2 804 are cyclically charged and discharged.

Although in various embodiments, the resistors may differ in value, inthe embodiment shown, R1 806 has a value of about 20 MOhms, R2 808 has avalue of about 75 Ohms, R3 810 has a value of about 75 Ohms, R4 812 hasa value of about 5 kOhms, R5 814 has a value of about 5 kOhms, and R6816 has a value of about 1 MOhm. Furthermore, the capacitors C1-C2 802,804 as shown can each have values of about 0.001 uf. These values maydiffer in alternative embodiments of the present disclosure.

In an example embodiment, the series combination of C1 802 and C2 804charge to about 50 KV (about 25 KV each) through the resistor chain806-816. When the voltage across the spark gap 818 reaches about 50 KV,the air in the spark gap ionizes into conductive plasma, shorting thetwo capacitors C1 and C2 together. The capacitors C1 802 and C2 804 thendischarge through R2, R3, R4, and R5 (808-814) producing a high voltagepulse on the right terminal of L1 822. In the embodiment shown, thissequence repeats at about a 20 ms rep rate.

L1 822, along with R7 824, R8 826, and the stray capacitance between ahigh voltage probe 830 and ground 832 form a tuned LRC circuit 834. Whenthe spark discharges C1 802 and C2 804, a short 50 KV pulse appears atthe right terminal of L1 822. This causes the LRC circuit 834 to produceits natural impulse response, which can be observed on the output of acurrent transformer 836.

In the embodiment shown, L1 has a value of about 1 MH, and the resistorsR7 824 and R8 826 each have resistance values of about 150 Ohms. Thesevalues may also vary in different embodiments of the present disclosure.

The presence of a flaw in the tire changes the circuit at the point ofthe high voltage probe 830. The exact nature of the flaw will determinethe nature of the change. Generally, the change will increase the straycapacitance, decrease the stray resistance, and change the thresholdvoltage where a spark will occur at the high voltage probe tip or acombination of all three. In any case, the distribution of energy fromC1 802 and C2 804 between the R2, R3, R4, R5 (808-814) path and the highvoltage probe path is altered, with more energy passing through the highvoltage probe. The circuit 800 uses this difference in energydistribution to detect flaws.

Measuring the relative energy level of each high voltage pulse throughthe probe and hence the energy dissipated in the high voltage probe pathenables detection of a wider variety of flaws and determination of thenature of the flaw itself. It also enables recording statisticalinformation about the flaws detected, such as a number or distributionof flaws detected on a tire or set of tires.

Referring now to FIGS. 9-13, schematics are shown for circuitry relatedto a high voltage assembly useable to detect flaws in tires, accordingto a further possible embodiment of the present disclosure. The circuitillustrated in the schematics of FIGS. 9-13 can be used as analternative to the circuit 800 of FIG. 8 to provide a high voltagesignal for detecting flaws in tires. In certain embodiments, the systemsdisclosed in FIGS. 9-13 correspond to the high voltage assembly 515 ofFIG. 5.

As seen in FIG. 9, the circuit portion 900 includes a communicationcircuit 902, a processing circuit 904, an input circuit 906, a triggercircuit 908, an AC circuit 910, a charge circuit 912, and a voltagesetting circuit 914. The communication circuit 902 includes an RS-232interface chip U12, interconnecting to data send and receive seriallinks, monitored at tap points TP36 and TP37, respectively. Thecommunication circuit 902 includes capacitors C39, C40, C41, C43, C44for managing voltage delivered to the chip.

The interface chip U12 also communicatively interconnects to theprocessing circuit 904 at a high voltage microcontroller U10, which incertain embodiments corresponds to high voltage microcontroller 518 ofFIG. 5. The high voltage microcontroller U10 interconnects to the inputcircuit 906, trigger circuit 908, AC circuit 910, charge circuit 912,and voltage setting circuit 914. Also included in the processing circuitare a monitor U11, as well as discrete components R51, R61. A connectorJ5 allows direct connection to and programming of the high voltagemicrocontroller U10, and connects via resistor R41 and capacitor C33.

The input circuit 906 includes a number of input signals (e.g. that canbe received from a control assembly), including a spare input, an enableinput, and a manual input. These inputs are each connected to the highvoltage microcontroller U10 by resistor-capacitor circuits (formed byR47, R55, and C34; R49, R56, and C38; R50, R57, and C37, respectively)as well as solid-state switches (shown as BJT-type transistors Q4, Q6,and Q7, respectively). An input voltage of about 5 VDC provides an uppersignal logic level to the input signals, and interconnects to thesignals via resistors R44, R45, and R48. Resistors R42 and R43 connectto diodes D16 and D17 which indicate activity of the high voltagemicrocontroller U10.

The trigger circuit 908 includes pulse outputs for outputting to a highvoltage probe. The pulse outputs are connected to the high voltagemicrocontroller U10 via signal conditioning circuitry, including a solidstate switch Q9, which activates the pulse outputs based on an outputfrom microcontroller U10. Additional circuitry, including resistors R9,R53, R54, diode D20, and capacitor C49 connect the pulse outputs to avoltage of about 5 VDC or ground, respectively.

The AC circuit 910 activates alternating current from the circuit 900.The AC circuit 910 includes an AND gate U9B that, when enabled, passes asignal through R52 to the gate of a solid state switch (BJT transistor)Q6, which causes a voltage difference between a 12 VDC source and acommon ground, activating a diode D19, connected in parallel with apower relay K1:A.

The charge circuit 912 activates a capacitor charging circuit used toactivate a pulse charging circuit (e.g. as seen in FIG. 10). The chargecircuit 912 includes an AND gate U9C that, when enabled, activates acharge and charge return output through use of resistors R58, R59. Thecharge return is tied (when the circuit is activated) to a commonvoltage by a solid state switch Q10 (BJT transistor).

The voltage setting circuit 914 activates a voltage of about 12 VDCthrough a coil, as directed by a diode and switch Q5 (BJT) whenactivated by an AND gate U9A through resistor R48.

FIG. 10 illustrates aspects of the high voltage assembly as a circuit1000, which includes functionality corresponding to the pulse chargingcircuit, charging capacitors, and SCR, as described above in FIG. 5. Thecircuit 1000 includes a pulse width modulating (PWM) controller U3,which receives the charge and charge return signals from the chargecircuit 912 of FIG. 9. When a pulse is directed to the circuit 1000 fromthe microcontroller U10, the PWM controller U3 generates pulse signalson output pins, which are passed through resistors R16, R65 to inducecurrent through transformer T1 which is arranged with capacitor C16,resistor R7, and diode D12 to form a current on an opposite side of thetransformer T1. Capacitors C20 and C21 are charged by the currentinduced through the transformer T1, and are discharged through pulseoutputs (to a high voltage probe) on an opposite side of anapproximately 25:1 step-up transformer T2 arranged to generate a highvoltage pulse at the high voltage probe based on the charge on C20 andC21.

Additional components that can be incorporated in the circuit 1000include a voltage rectifier U18, as well as indicators and othercomponents leading to a comparator U5. The comparator U5 compares thehigh and low voltages to determine whether the capacitors are charged.Once the capacitors are charged, photocoupler U4 is activated indicatingthat the high voltage probe can be discharged.

As illustrated in FIG. 5, a signal is output from a high voltage probeand through a current transformer to detect the current. Referring nowto FIG. 11, a return signal from a current transformer is received atconnector J6, which passes that signal through a peak detector circuitformed from capacitors C29 and C30, resistors R36 and R37, and diodeD15, forming an RC circuit. A D/A converter U8 (as powered via voltageregulator U13 and related capacitances C46, C47, C31) forms an analogsignal from an input value for the expected threshold received at thecurrent transformer, as indicated by control circuitry (e.g. receivedfrom the control circuitry of FIGS. 6-7). A comparator U7 compares theexpected threshold from the converter U8 to the peak-detected signalreceived at J6, which is stored on the capacitors C29 and C30. Thecomparator U7 outputs a logic level corresponding to a time at which thevoltage of the discharging capacitors remains above a threshold ofapproximately 1V to 1.2V. As previously mentioned, this logic levelduration typically is about 2 ms, however it may vary depending upon theinput energy to the high voltage probe and the element values of theresistors and capacitors in the peak detector RC circuit. The logiclevel output is passed back to the high voltage microcontroller U10 ofFIG. 9, which compares the signal to an expected signal (e.g. anumerical time value) to determine whether a flaw exists at the currentlocation on the tire. The microcontroller U10 can format a message andtransfer fault information or other test data back to control circuitryvia the RS-232 interface as well.

FIGS. 12-13 provide signal conditioning for input voltages and controlsignals received into the circuitry of FIGS. 9-11. FIG. 12 illustrates acircuit 1200 that provides input conditioning for power signals used bythe high voltage assembly. The circuit 1200 receives a high voltagesignal at connector J1, which passes through a fuse F3 and acrosscapacitors C3, C4 and transformer L1 to a pair of power relays K1B andK1C. The signal passes a bridge rectifier BR1 to prevent negativevoltages. After the signal passes through resistor R1, it reaches anAC/DC converted U6 to form a 12 VDC output. Indicator and signalstabilizing circuitry D1, C5, R2, and D2 ensure a clean input signal toU6 and activate an indicator when voltage is present on the line.

FIG. 13 illustrates a circuit 1300 that receives DC voltage input andsignal inputs at connector J3. In the embodiment shown, the RS-232 sendand receive signals (Tx, Rx), as well as the manual, enable, and spareinputs pass directly through from the jumper with no additionalconditioning (with the RS-232 signals capacitively coupled viacapacitors C14 and C15 to a common voltage). When the control circuitryof FIGS. 6-7 is used in conjunction with the high voltage circuit ofFIGS. 9-13, an RS-232 port (seen as IC3 of FIG. 7) provides datacommunication with microcontroller U10 of FIG. 9 to send pulse,threshold, and energy level commands to the high voltage circuit. Othermessages can be exchanged via the RS-232 interface as well.

A DC voltage input is passed through fuse F4, diode D5, and pastcapacitors C8, C9, and inductor L3 to reach connector J2. Connector J2allows jumpered enabling and disabling of the DC voltage, whose presenceat J3 is indicated by LED D6. Additional capacitive couplings C10, C11,C12, and C13 are interspersed with voltage regulators U1 and U2.Additional LEDs D7, D8 and associated resistors R4 and R5 are used toindicated a presence of a voltage. Diodes D3, D4 are connected acrossthe voltage regulators U1 and U2, respectively.

Referring now to FIGS. 9-13 generally, the high voltage circuits900-1300 can be configured to receive commands via the RS-232 interfacefrom the control circuit of FIGS. 6-7. These commands can include aninput energy level to be generated by the high voltage probe, and anexpected observed threshold energy at the current transformer oppositethe probe. The expected observed threshold energy corresponds to a levelabove which a flaw is determined to exist.

Each pulse is independently directed to the high voltage circuits, whichin turn generate a pulse on a high voltage probe and assess returnvoltage received (e.g. at comparator U7) to sense faults in a tire. Inresponse to a sensed fault, the circuitry can output a return message tothe control circuitry, which can store and catalog the sensed fault,halt a motor arranged to rotate the tire for analysis, or outputadditional pulses of the same or different values to validate thefinding of a flaw in the tire. Through use of such a pulse-by-pulsesystem using pulses of differing energy levels, it is expected thatvarious types of flaws (e.g. holes, separations, or other flaw types)can be detected and categorized in terms of observed response todiffering energy levels.

In certain embodiments of the system, particularly those incorporatingcircuits analogous to the high voltage circuits 900-1300, statisticalanalysis of those flaws could be performed, either within the controlcircuitry, the high voltage circuitry (e.g. at U10), or within acomputer communicatively connected to the tire tester. Flaw events canbe stored in a memory associated with the tire tester or associatedcomputer. These flaw events can be stored in a data record such as aflaw record, which includes an indication of the flaw, the tire on whichthe flaw is detected, the time at which the flaw is detected, theseverity and type of the flaw, the location of the flaw on the tire, andraw data collected regarding the flaw (e.g. energy thresholds andobserved capacitor discharge time). Additional tire and test informationcan be tracked as well, such as the model and size of the tire, anidentifier of the tester performing the test, and other test settings.Subsequently, the stored flaw records can be examined to perform thisstatistical analysis. For example, flaw records can be used to correlatevarious data such as the location of a flaw (e.g. in the wall, tread, orother location), types of flaws, number of flaws per tire, number offlaws in a series of tires, number of flaws for a particular type oftire, or other measures. This information can allow a user to detect arecurring type of flaw or flaw location in a particular brand of tire orunder typical use. For example, detection of a recurring type orlocation of a flaw in a common brand of tire under disparate usageconditions may correspond to a design problem in the tire. Suchstatistical analysis can also include analysis of responses to knownflaws of differing types to determine expected energy level responsesbased on the type of flaw.

In certain embodiments, multiple tire defect testers can be used incombination, such as at a tire manufacturing, maintenance, or testingfacility. In such instances, the tire defect testers can becommunicatively networked, and data from multiple testers can becompiled in one of the testers or a database of a computing systemconnected to the network. In networked embodiments, this data can beanalyzed centrally by a tester or computing system, and can be used todetect overall flaws in a tire testing, maintenance, or manufacturingprocess. Flaw records can also be used to halt or alter upstream actionson tires (e.g. manufacturing processes or maintenance actions), or cansound an alarm if flaws are detected at a greater than acceptable rate.

Additional circuitry and circuit routing can be incorporated into thesystems described herein, such as the routing, signal conditioning, andsignal/clock generation components shown in FIGS. 5-13. Although inFIGS. 5-13 and the corresponding detailed description, certainintegrated circuits and discrete component values are described, othervalues can be used as well to provide functionality analogous to thatdescribed herein. Furthermore, other arrangements of circuits andcomponents can be used to achieve the functionality described herein.

Referring generally to the systems described in FIGS. 5-13 above, incertain embodiments, the controllers described herein generate alltime-based operations from a single frequency standard. Use of a singlefrequency standard ensures accurate timing for all functions, ascompared to an analog time based controller. Digital control alsoprovides consistency between control board assemblies, leading to ahigher degree of interchangeability and less adjustments and set up timein the field.

In certain further embodiments, circuitry used in the controllers of thepresent disclosure make extensive use of surface mount technology. Useof surface mount technology reduces the size of the controllerconsiderably and also permits machine assembly, reducing the chance ofhuman error in assembly. The controller also takes advantage of changesin connector technology. Connections are made through field installableconnectors, allowing both rapid installation and rapid change out of thecontrol board, without the risk of incorrect wiring.

The controllers described in the present disclosure offer severaladvantages. For example, measuring the energy enables detecting andrecording more information than merely detecting the presence or absenceof a flaw. A controller reads the operator controls, runs the testsequence, measures, evaluates the results, and provides indications tothe operator. Putting all of these functions under digital programmablecontrol means the functions are not subject to environmental changessuch as heat, humidity and age, which makes the operation more reliableand repeatable.

The above specification, examples and data provide a completedescription of the manufacture and use of the composition of theinvention. Since many embodiments of the invention can be made withoutdeparting from the spirit and scope of the invention, the inventionresides in the claims hereinafter appended.

The invention claimed is:
 1. A method of testing tires for defects, themethod comprising: charging a capacitor; generating an energy signal,the generating an energy signal comprising selectively triggering arectifier and discharging the capacitor; passing the energy signalthrough a transformer to increase a voltage of the energy signal;directing the energy signal toward a first location on a first surfaceof a tire; detecting an attenuated energy signal on a second surface ofthe tire, the second surface opposing the first surface; and comparingthe attenuated energy signal to a predetermined energy signal value todetermine the presence of a flaw in the tire.
 2. The method of claim 1,wherein the predetermined energy signal value includes a thresholdenergy signal value.
 3. The method of claim 2, wherein the thresholdenergy signal value is a signal value selected by a user.
 4. The methodof claim 1, wherein the predetermined energy signal value includes apreviously-observed energy signal value.
 5. The method of claim 1,further comprising: rotating the tire; charging the capacitor;generating a second energy signal, the generating a second energy signalcomprising selectively triggering the rectifier and discharging thecapacitor; passing the second energy signal through a transformer toincrease a voltage of the second energy signal; directing the secondenergy signal toward a second location on the first surface of the tire;detecting a second attenuated energy signal on the second surface of thetire; and comparing the second attenuated energy signal to thepredetermined energy signal value to determine the presence of a flaw ina tire at the second location.
 6. The method of claim 1, furthercomprising rotating the tire.
 7. The method of claim 6, furthercomprising, upon determining the presence of a flaw in the tire, haltingrotation of the tire to indicate the location of the flaw.
 8. The methodof claim 1, further comprising periodically generating energy signals tobe directed toward a surface of the tire by an energy source.
 9. Themethod of claim 1, further comprising storing a record of the flaw in amemory.
 10. The method of claim 1, further comprising performingstatistical analysis of flaws detected by the tire tester.
 11. Themethod of claim 1, further comprising, upon detection of a flaw in thetire, activating a tire flaw indicator.
 12. The method of claim 1,further comprising: repeating the acts of charging a capacitor,generating an energy signal, passing the energy signal through atransformer, and directing the energy signal toward a first location ona surface of the tire.
 13. The method of claim 12, wherein repeating theacts of charging a capacitor, generating an energy signal, passing theenergy signal through a transformer, and directing the energy signaltoward a first location on a surface of the tire generates a waveform.14. The method of claim 13, wherein the waveform is a saw-tooth waveform.